Most RE systems can be credited with reducing three greenhouse gases:
CO2, CH4 and N2O.
These are all waste products from
fossil fuel combustion.

In addition, RE systems reduce criteria pollutants which affect climate
indirectly, cause acid rain, and are related to respiratory problems in humans and other animals.
We track and certify those reductions as well, because some have a market value
(SO2 & NOX), and others could attain
commercial value in the future, especially if they reduce potential outlays in the health industry.

ICBE assigned emission reduction values

Greenhouse gases produced per kWh vary wildly from utility to utility and country to
country. For initial registrations, the ICBE uses an approximate average to estimate
emissions reductions. Full registration includes reduction estimation based on location-specific
emission production figures sourced from the EPA,
IEA, or equivalent authority in the country of
registration.

Below are the GHG emission values used to express reductions achieved by 1
kWh produced from solar thermal, solar electric, wind and hydro-electric systems at
initial registration into the ICBE Renewable Energy Database™.

They come from 1996 US electric utility related emissions, rounded to a convenient
number.

Greenhouse Gases

CO2

1 kg

CH4

0.00001 kg

N2O

0.00001 kg

SF6

0.00000055 kg

Criteria Pollutants

CO

0.00015 kg

NMVOC's

0.00002 kg

SO2

0.005 kg

NOx

0.0025 kg

Global Warming Potential, or GWP

Each greenhouse gas has active radiative, or heat-trapping properties.
To compare greenhouse gases, they are indexed according to their Global Warming
Potential. GWP is the ability of a GHG to trap heat in the atmosphere relative to an
equal amount of carbon dioxide. Carbon dioxide assumes the value one (1). Carbon
dioxide, though the most prevalent, is the least powerful GHG.

Greenhouse gases can now be expressed in carbon dioxide equivalents. A unit you'll see
often is MMTCDE, or million metric tons of carbon dioxide equivalents.

To calculate emission reductions achieved by renewable energy systems, the
assumption is that a utility would otherwise have provided the energy now produced by
the RE system. Knowing how many grams of GHG's a utility produces to generate and
deliver 1 kWh, combined with the usage characteristics and the performance of your system
allows us to calculate GHG reductions. After certification, these reductions become eligible
for trading.

These next graphs show greenhouse gases and their global warming potential, and
GHG's from all sectors of the 1996 US economy, expressed in
GWP.

CO2

1

CH4

21

N2O

310

HFC's

140 ~ 11,700

PFC's

6,500 ~ 9,200

SF6

23,900

The total US production of GHG's in 2000 was 7,000.1 MMTCDE,
14.2% above 1990 baseline levels.

Overview

Documentation of ERC's extended by the ICBE is in the public domain and available on this web
site. RE systems are credited with Greenhouse Gas reductions
(ERC's) as well as several other pollutants (where available) at the end of each calendar or
production year. System owners can use their on-line account to update system info, and sell,
retire, or re-invest their ERC's.

Please note that Renewable Energy (excluding biomass) is almost completely
emissions free and eligible for a variety of emission reductions. Sequestration
projects, however, where carbon is harvested from the atmosphere and stored in trees,
only reduces carbon dioxide, not any other greenhouse gas.

The value of emission reductions is expected to rise as carbon taxes and other
regulatory measures strengthen to meet the
reduction targets negotiated under the Kyoto Protocol.